Scroll-type compressor with cooling fins included inside a discharge port of a compressed gas

ABSTRACT

A scroll-type compressor  1  of the present invention comprises a fixed scroll  30,  a movable scroll  51  which orbits so that it slides along the fixed scroll  30,  draws, and compresses gas, and a housing  3  which includes a discharge port  6  from which the gas compressed by the movable scroll  51  is discharged; wherein a cooling fin  35,  which directly contacts at least a part of the compressed gas, receives heat from the compressed gas, and reduces the temperature of the compressed gas, is included inside the discharge port  6.  In the scroll-type compressor in the present invention the cooling fin is provided in the discharge port. When the cooling fin is provided in the discharge port, and not around the discharge port, the discharge gas of high temperature directly contacts the cooling fin, so that the cooling efficiency of the compressor is improved.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a scroll-type compressor. More particularly, the present invention relates to a scroll-type compressor that compresses gas to be supplied to a fuel cell, etc.

[0003] 2. Description of the Related Art

[0004] There are various kinds of compressors such as a screw-type compressor, a two lobe rotor type compressor, a rotary-type compressor, and a scroll-type compressor. The scroll-type compressor is compact and light, and generates little vibration and noise, so that it has broadly been used in various applications such as refrigerating use, air-conditioning use, etc. When compressed gas in the scroll-type compressor is cooled, in conventional cases, a cooling chamber is normally arranged around a discharge port of the compressed gas, as in the case described in Japanese unexamined patent publication (Kokai) No. 8-247,056.

[0005] FIG.4 is an axial cross-sectional view of a conventional scroll-type compressor. A housing 100 of a conventional compressor comprises a front casing 101, an end plate 102, and a rear casing 103.

[0006] In the center of the front casing 101 and the end plate 102, a discharge port 104 is provided. Also, a cooling chamber 120 is provided between a recess portion of the front casing 101 and the end plate 102. A fixed scroll 105 is provided and stands inside the front casing 101. Moreover, a suction chamber 106 is provided on the outer circumferential side of the fixed scroll 105 and a discharge chamber 107 is provided in the center of the inner circumferential side of the fixed scroll 105. The discharge chamber 107 and the discharge port 104 are separated by a discharge valve 108.

[0007] On the other hand, one end of a drive shaft 109 of crank shape is arranged on a rear end of the rear casing 103 so that rotation is possible. A movable plate 111 on which a movable scroll 110 is installed and stands is also arranged on the top end of the drive shaft 109 so that rotation is possible.

[0008] When the drive shaft 109 rotates and the movable scroll 110 orbits, air in a space enclosed by the fixed scroll 105 and the movable scroll 110 moves toward the center region of the fixed scroll 105, while being compressed. The compressed air which arrives at the discharge chamber 107 passes through the discharge valve 108, and is discharged to the outside of the compressor from the discharge port 104.

[0009] Cooling water flows into a cooling chamber 120 through a cooling water inflow port, which is not shown. The cooling chamber 120 is contiguous to the discharge port 104, so that heat of the compressed air in the discharge port 104 is transmitted from the compressed air to the cooling water. The cooling water to which heat is transmitted and whose temperature is increased flows out of the compressor through a cooling water outflow port, which is not shown.

[0010] However, in the conventional scroll-type compressor the cooling chamber which acts as a cooling means is provided around the discharge port and the heat of the compressed gas is transmitted to the cooling water through the thick wall of the discharge port. Therefore, the cooling efficiency, of the conventional scroll type compressor, for the compressed gas has been low.

SUMMARY OF THE INVENTION

[0011] To solve the above-mentioned problems, a scroll-type compressor of the present invention comprises a fixed scroll, a movable scroll which orbits so that it slides along the fixed scroll and which draws and compresses gas, and a housing which includes a discharge port from which the gas compressed by the movable scroll is discharged, wherein a cooling fin which directly contacts at least a part of the compressed gas, receives heat from the compressed gas, and reduces the temperature of the compressed gas, is included inside the discharge port.

[0012] That is, in the scroll-type compressor in the present invention a cooling fin is provided in the discharge port. When the cooling fin is provided in the discharge port, not around the discharge port, high temperature discharge gas directly contacts the cooling fin. Therefore, the cooling efficiency of the scroll-type compressor in the present invention is improved.

[0013] The present invention may be more fully understood from the description of the preferred embodiments of the invention set forth below, together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In the drawings:

[0015] FIG.1 is an axial cross-sectional view of a scroll-type compressor in the first embodiment.

[0016] FIG.2 is a sectional view taken along line A-A in FIG.1.

[0017] FIG.3 is a radial cross-sectional view of a discharge port portion of a scroll-type compressor in the second embodiment.

[0018] FIG.4 is an axial cross-sectional view of a conventional scroll-type compressor.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Some embodiments of the scroll-type compressor of the present invention will be described below.

[0020] First Embodiment

[0021] FIG.1 is an axial cross-sectional view of a scroll-type compressor in the present embodiment. A scroll-type compressor 1 in the present embodiment is used to compress air supplied to a fuel cell. Also, the scroll-type compressor is driven by an electric motor, which is not shown. A housing of the scroll-type compressor 1 in the present embodiment comprises a front casing 3 which has a recess 39 in the end face of the discharge side of the front casing 3, an end plate 4 which is provided on the end face of the discharge side thereof, and a rear casing 5 which is provided on the end face of the motor side of the front casing 3. All these members are made of an aluminum alloy.

[0022] A fixed scroll 30 is provided inside the front casing 3 and extends in an axial direction from an inner wall 36. A suction chamber 31 is also formed on an outer circumferential side of the fixed scroll 30 and a discharge chamber 32 is formed in the center region of the fixed scroll 30. A discharge valve 33 which opens only in a discharge direction is provided on the discharge side of the discharge chamber 32 and a discharge port 6, which penetrates through the end plate 4 and communicates with a fuel cell, is provided on the downstream side of the discharge valve 33. Also, cooling fins 35 integrally formed with the front casing 3 are provided in the discharge port 6. On the other hand, a cooling chamber 7 which includes heat radiating fins 70 installed and standing inside the cooling chamber 7 is provided between the recess 39 of the front casing 3 and the end plate 4.

[0023] FIG.2 is a section view taken along line A-A in FIG.1. The cooling chamber 7 is formed in a U shape and surrounds the discharge port 6, an inflow port 37 into which cooling water flows is provided on one end of the cooling chamber 7, and an outflow port 38 from which the cooling water flows out is provided on the other end thereof. The cooling chamber 7 is also a component of a cooling circuit, which is not shown. In the cooling circuit, a radiator which cools a high temperature cooling water flowing out from the outflow port 38, a pump which allows cooled cooling water to flow into the inflow port 37, and so on, are arranged. Pure water which is produced through a fuel cell reaction in the fuel cell is used as the cooling water which circulates in the cooling circuit.

[0024] On the other hand, as shown in FIG.1, one end of the drive shaft 50 is arranged on the motor side end of the rear casing 5 through a ball bearing so that rotation is possible. The drive shaft 50 has a crank shape. A circular-shaped movable plate 52 is arranged on the other end of the drive shaft 50 through a bearing so that rotation is possible and also a balance weight is arranged so that the drive shaft 50 rotates in a balanced manner. A movable scroll 51 is provided on the movable plate 52 and extends out in the axial direction therefrom. The drive shaft 50 is connected to a rotating shaft of the motor, which is not shown. The end portion of the fixed scroll 30 extending from the inner wall 36 of the front casing 3 comes into contact with the surface of the movable plate 52 which is opposed to the inner wall 36. On the other hand, the end portion of the movable scroll 51 comes into contact with the inner wall 36. That is, the fixed scroll 30 and the movable scroll 51 are arranged between the inner wall 36 and the movable plate 52, they overlap each other, and the fixed scroll 30 is arranged in a status being turned, in just 180 degree, with respect to the movable scroll 51. A space in which air is compressed is defined by the inner wall 36, the fixed scroll 30, the movable plate 52, and the movable scroll 51. One end of a movable shaft 55 is arranged on the outer circumferential side of the movable plate 52 through a ball bearing so that rotation is possible. The movable shaft 55 also has a crank shape as same as the drive shaft 50 and has a balance weight on one end thereof. The other end of the movable shaft 55 is also arranged on the rear casing 5 through a ball bearing so that rotation is possible.

[0025] When the drive shaft 50 is rotated by the motor, a rotational force is transmitted to the movable plate 52 and the movable plate 52 rotates around the drive shaft 50 which defines the center of the rotation. The movable scroll 51 orbits so that it slides along the fixed scroll 30. The self-rotation of the movable scroll 51 is prevented by the movable shaft 55.

[0026] Air is drawn from an air suction port, which is not shown, and flows into the suction chamber 31 connected to the air suction port. When the movable scroll 51 orbits, air in a space enclosed by the fixed scroll 30 and the movable scroll 51 moves toward the center region of the fixed scroll 30 while being compressed. The compressed air then arrives at the discharge chamber 32 in the center of the fixed scroll 30, flows into the discharge port 6 through the discharge valve 33, and is discharged to the outside of the compressor from the end of the discharge port 6.

[0027] Cooling water flows into the cooling chamber 7 from the inflow port 37, as shown in FIG.2, receives the heat of the compressed air, in the discharge port 6, at the cooling chamber 7, and then flows out from the outflow port 38. The cooling water flowing out is cooled by a radiator, which is not shown, and is forced back into the cooling chamber 7 again by a pump, which is not shown. That is, the cooling water is circulated in the cooling circuit, while a temperature increase, and a decrease, of the cooling water are repeated in turn. However, a part of the cooling water flowing out from the outflow port 38 is disposed and alternatively pure water produced in a fuel cell is adequately complemented into the cooling circuit.

[0028] The cooling fins 35 in this embodiment are made, integrally with the front casing 3, by casting.

[0029] Second Embodiment

[0030] FIG.3 is a cross-sectional view around the discharge port 6 of a scroll-type compressor 1 in this embodiment. In FIG.3, the same symbols are attached to the same components as in the first embodiment. The cooling fins 35 in this embodiment are constructed as separate members from the front casing 3. The cooling fins 35 are made by a casting. Also, the inner passages 34 are formed in the cooling fins 35 in this embodiment. The inner passages 34 are fabricated by obliquely boring holes in both ends of the cooling fins 35, after casting, and by connecting both holes. The fabricated cooling fins 35 are assembled in the front casing 3 in a procedure in which, at first, cuts are formed in the discharge port 6 in an axial direction from the discharge end and, next, the cooling fins 35 are inserted in the cuts and, lastly, the end plate, which is not shown, is placed on the discharge port 6. The different constitutions, of the scroll-type compressor in this embodiment, which differ from those in the first embodiment, are that the cooling fins are separately constructed from the front casing and that the inner passages are formed by boring in the cooling fins. Other constitutions of the scroll-type compressor in this embodiment are same as those in the first embodiment.

[0031] The scroll-type compressor of the present invention has the cooling fins in the discharge port. Therefore, it can effectively cool the compressed gas to be discharged.

[0032] The variants and modifications of the present invention and the effects thereof become more apparent from the following descriptions.

[0033] Though the shape of cooling fins is not particularly restricted, preferably the shape thereof has a low flow resistance against the discharge flow of the compressed gas so that the discharge flow is not disturbed and the temperature of discharge gas is not increased. Also, the surface areas (the heat transferring areas) of the cooling fins are preferably large so that the cooling efficiency of the compressor can be improved. For the above reasons, concretely, the cooling fins preferably have a shape such that the cooling fins extend in an axial direction of the discharge port. The installing location of the cooling fins is also not particularly restricted as far as they are located within the discharge port, but the area which is close to the discharge valve and in which the temperature of the compressed gas is high is preferable in order to improve the cooling efficiency. In order to increase the heat transferring areas the cooling fins may be provided on the whole axial length of the inside of the discharge port. Also, the cooling fins may be integrally made with the members forming and surrounding the discharge port or may be separately made from the members. When the cooling fins and the members forming and surrounding the discharge port are integrally made, the time spent for the fabrication thereof can be shortened. Further, when they are separately made, the cooling fins can be fabricated in a relatively easy manner even if the shape of the cooling fins is complicated.

[0034] The cooling chamber may be provided on at least a part of the outer circumference of the discharge port, while the cooling chamber is arranged separate from the cooling fins. The cooling fluid which is used for cooling the compressed gas is supplied into the cooling chamber. The cooling fluid receives the heat of the compressed gas, so that the cooling efficiency can be more improved. The cooling chamber may be provided either on the whole areas of the outer circumference of the discharge port or only on a partial area thereof. The larger installation areas of the cooling chamber are preferable, because the cooling efficiency can be improved. If fins are extended in the cooling chamber, the heat transferring areas are increased and the cooling efficiency can be more improved. The cooling chamber constitutes a part of a cooling circuit, though it is positioned separate from the cooling circuit. Cooling fluid which has a lower temperature than that of the compressed gas should be supplied to the cooling chamber by the cooling circuit. The cooling circuit may, for example, comprise a cooling method which cools the cooling fluid heated by the compressed gas, a pumping method which supplies the cooling fluid, and so on, and may circulate the cooling fluid in the cooling circuit. Moreover, a cooling fluid supply method and a cooling fluid disposal method may additionally be provided in the cooling circuit and the cooling fluid may circulate in the cooling circuit, while some of cooling fluids are replaced by new fluids. In addition, if sufficient quantity of low temperature cooling fluids is supplied, the cooling fluids heated by the compressed gas may be disposed without circulating in the cooling circuit.

[0035] Moreover, the kinds of the cooling fluids are not particularly restricted. Fluids, such as water, air, etc., with lower temperature than the compressed gas can be applied.

[0036] Preferably, the cooling fins may also be provided with inner passages. Cooling fluid is supplied to the inner passages which are formed in the cooling fins and thereby the cooling efficiency, of the compressor, for the compressed gas can be more improved. The inner passages also constitute a part of the cooling circuit, though they are provided separate from the cooling circuit. The cooling circuit in this case can also have a similar construction as that of the cooling circuit, for the cooling chamber, described above. The compressed gas directly contacts the cooling fins. The cooling efficiency of the compressor can be more improved by supplying the cooling fluid to the inner passages in the cooling fins.

[0037] Moreover, the cooling chamber may preferably be connected to the inner passages. Thus, a single cooling circuit allows the cooling fluids to be supplied to both the cooling chamber and the inner passages. That is, respective cooling circuits for the cooling chamber and the inner passages need not to be provided separately. Therefore, the cooling circuit can be simplified and the location areas of the cooling circuit in the compressor can be reduced.

[0038] The scroll-type compressor of the present invention is especially advantageous for compressing gas supplied to a fuel cell. In the automobile industry, a demand for electric cars, to which a fuel cell supplies energy, is increasing. A scroll-type compressor that is compact and light is expected to be used to supply compressed gas to the fuel cell. When gas is supplied to the fuel cell, it must be previously humidified before it is employed in a fuel cell reaction. Therefore, a water vapor exchange membrane for humidifying compressed gas is provided in the outlet side of the discharge port of the compressor and the water vapor exchange membrane can resist a temperature of around 140° C. Moreover, some components of the fuel cell only resist a temperature of around 100° C. Therefore, the compressed gas should previously be cooled in the compressor to the condition approximately satisfying the above temperature conditions. When the scroll-type compressor of the present invention is applied to compress the supplied gas, the compressed gas, that is, the gas supplied to a fuel cell, can be cooled to around the temperature that satisfies the above-mentioned temperature conditions. Therefore, the fuel cell and the components thereof can be protected from heat. In addition, in a fuel cell pure water is produced as a by-product of a fuel cell reaction and can be effectively used as the cooling fluid supplied to the cooling chamber and the inner passages of the scroll-type compressor. The gases supplied to the fuel cell include air, oxygen, etc., as an oxidizer, and hydrogen etc., as a fuel. The scroll-type compressor of the present invention can be used for all of the above gases.

[0039] Though several aspects of the scroll-type compressor of the present invention are explained above, the aspects of the scroll-type compressor of the present invention are not particularly limited to the aspects described above. The variants and modifications, of the aspects, which can easily be performed by those of ordinary skill in the art, can be realized.

[0040] While the invention has been described by reference to specific embodiments chosen for the purpose of illustration, it should be apparent that numerous modifications could be made thereto by those skilled in the art without departing from the basic concept and scope of the invention. 

1. A scroll-type compressor, comprising a fixed scroll, a movable scroll which orbits so that it slides along the fixed scroll, draws, and compresses gas, and a housing which includes a discharge port from which gas compressed by said movable scroll is discharged; wherein a cooling fin which directly contacts at least a part of the compressed gas, receives heat from the compressed gas, and reduces the temperature of said compressed gas, is included inside the discharge port.
 2. A scroll-type compressor, as set forth in claim 1, wherein the housing comprises a cooling chamber on at least a part of an outer circumference of the discharge port.
 3. A scroll-type compressor, as set forth in claim 1, wherein the cooling fin comprises an inner passage.
 4. A scroll-type compressor, as set forth in claim 1, wherein the housing is provided with a cooling chamber on at least a part of an outer circumference of the discharge port, the cooling fin is provided with inner passage, and said cooling chamber is connected to said inner passage.
 5. A scroll-type compressor, as set forth in claim 1, is used to compress gas supplied to a fuel cell. 